Preparation of vinylalkoxysilanes

ABSTRACT

THE PREPARATION OF VINYLALKOXYSILANES WITH INVOLVES CONTACTING (IN A CLOSED SYSTEM OR OPEN CONTINUOUS SYSTEM) AN ALKOXY-SUBSTITUTED DISILANE WITH AT LEAST A STOICHIOMETRIC AMOUNT OF AN ALCOHOL, E.G., METHANOL, AND AN ALKYNE, E.G., ACETYLENE, AT A TEMPERATURE OF AT LEAST 175*C. THE RECOVERED VINYLAKOXYSILANES ARE PARTICULARLY USEFUL AS CROSSLINKERS AND/OR CHAIN EXTENDERS FOR A VARIETY OF ELASTOMERS.

United States Patent O 3,576,024 PREPARATION OF VIN YLALKOXYSILANES William H. Atwell, Midland, Mich., assignor to Dow Corning Corporation, Midland, Mich. No Drawing. Filed Aug. 11, 1969, Ser. No. 849,166 Int. Cl. C07f 7/04, 7/18 US. Cl. 260-4483 8 Claims ABSTRACT OF THE DISCLOSURE mel's- This invention relates to the preparation of vinylalkoxy- Silanes by contacting alkoxy-substituted disilanes with a stoichiornetric amount of an alcohol and an alkyne.

Heretofore, the principal method for preparing such vinylalkoxysilanes has required the use of a catalyst, e.g., chloroplatinic acid or the like. In contrast to the aforementioned prior art method, the present method avoids the use of a catalyst thereby providing significant economic advantages as well as preventing the possibility of attendant hazards which may be encountered in the use of certain catalysts commonly employed for such purposes. In addition, it has been found that significantly greater yields are obtained when following the method described herein.

In accordance with the above, the present invention relates to a method for preparing vinylalkoxysilanes com prising (A) Contacting in a closed system (1) a disilane f the formula in which R is an alkyl radical of from 1 to 6 carbon atoms inclusive,

R is selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms inclusive, and a phenyl radical,

n has a value of 1 to 2 inclusive, with (2) At least a stoichiometric amount of an alcohol of the formula ROH and an alkyne of the formula R"CECR" in which R is as above defined, R" is selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms inclusive, a phenyl radical, and a hydrogen atom,

(B) Heating the above admixture to a temperature of at least about 175 C., and

(C) Thereafter recovering the vinylalkoxysilane.

As noted above, R can be an alkyl radical of from 1 to 6 carbon atoms inclusive such as the methyl (preferred), ethyl, propyl, isopropyl, butyl, t-butyl, amyl and the hexyl radical. The corresponding alkoxy radical on the disilane (1) can therefore be the methoxy (preferred), ethoxy, propoxy, isopropoxy, butoxy, amyloxy, and the hexoxy radical.

R can be an alkyl radical of from 1 to 6 carbon atoms inclusive as illustrated for R above or a phenyl radical and R" may be an alkyl radical of from 1 to 6 carbon 3,576,024 Patented Apr. 20, 1971 atoms as illustrated for R above, a phenyl radical, or a hydrogen atom, and preferably R" is the hydrogen It may, of course, have a value of 1 or 2.

By the term closed system one merely means that the reaction is conducted under conditions whereby the reaction is not open to the atmosphere and thus, the reaction is necessarily carried out under pressure which is generated and determined by the particular temperature selected. This is readily accomplished by means of a sealed ampule or a metal pressure vessel.

It is necessary that the reaction be conducted at a temperature of about C. since at lower temperatures the reaction is not initiated or proceeds at such a slow rate that it is in essence impractical. For purposes of the present invention, it has been found that a temperature of about 200 C. to 250 C. is particularly preferable.

This invention also relates to a method for preparing the vinylalkoxysilanes via the aforementioned procedure with the exception that the reaction is carried out in a continuous open system at a temperature of at least about 350 C.

By the term continuous open system one merely means that the reaction is conducted under conditions whereby the reactants are passed continuously to a heated tube or the like under atmospheric pressure.

Under this system it is necessary that the reaction be conducted at a temperature of at least about 350 C. and preferably from about 400 C. to about 450 C.

Regardless of the system selected, a temperature of 500 C. should not be exceeded because it introduces the possibility of pyrolysis thereby substantially decreasing the yields of the vinylalkoxysilanes.

Under either system, the order of contacting the ingredients (1) and (2) is unimportant and any convenient technique can be used. However, it is important that the disilane (1) and the mixture (2) be simultaneously heated in order to achieve the desired objectives.

With respect to the alcohol and alkyne (2), at least a stoichiometric amount should be employed. An excess of the alcohol is preferred since if favors higher yields of the vinylalkoxysilanes.

The following examples are illustrative only and are not intended to limit the invention which is properly delineated in the appended claims.

EXAMPLE 1 Ten and one-half grams (0.05 mol) of the disilane CH3 (onions i-suocflm and 5.4 grams (0.1 mol) of the dimethylacetylene and 3.2 grams (0.1 mol) of methanol were sealed in an ampule and heated at 200 C. for 8 to 10 hours. Subsequent to cooling, the excess reagents and by-produced CH Si(OCH were removed by distillation means. Continued distillation provided 3.5 grams (44%) of a vinylalkoxysilane of the formula CH3 oHiC=i7si(oCH3)2 Ill H3 The structure was characterized by infrared, n.m.r., and

mass spectral analyses as well as by methylation to the known structure,

CH: CHaC=(l] S 1(CH3)3 EXAMPLE 2 OHaO SiSiOCHa and 23.5 grams (0.44 mol) of dimethylacetylene and 13.9 grams (0.44 mol) of methanol were heated at 225 C.

plete consumption of the disilane and the formation (22.0 area percent) of a viuylalkoxysilane of the formula ncicsuoomn H CH3 EXAMPLE 5 Seventeen and eight-tenths (0.1 mol) grams of the disilane for 18 to 20 hours. Distillation provided 7.9 grams (38%) (CH of a vinylalkoxysilane of thecforrnula CHEO 510 CH3 i H02 CHaOZCSlOCHs and a mixture of 10.8 grams (0.2 mol) of dimethyl- H (011;): 1r acetylene and 3.2 grams (0.1 mol) of methanol were The structure was characterized by infrared, n.m.r., and passed (5 .0 ml./ hour) through a heated (400 C.) quartz mass spectral analyses as well as by methylation to the tube. G.l.p.c. analysis of the reaction admixture showed known structure, total utilization of the disilane and the formation (44.3

area percent) of a vinylalkoxysilane of the formula CHaC=CSi(CHa)a E li CH3G=CSiOCH EXAMPLE 3 H (CHM Twenty-one grams (0.1 mol) of the disilane EXAMPLE 6 Nineteen grams (0.1 mol) of the disilane (CH O)2SiSi(OCHa)2 (3H3 (3'13 omonsi-siocm and 10.8 grams (0.2 mol) of dimethylacetylene and 3.2 (CHW grams (0.1 mol) of methanol were passed (5 mL/hour) and 11.0 grams (0.2 mol) of dimethylacetylene and 3.2 through a quartz tube at 400 C. G.l.p.c. analysis. showed grams (0.1 mol) of methanol were passed (5.0 m1./ hour) complete utilization of the disilane and the formation through a quartz tube at a temperature of 400 C. (31.0 area percent) of a vinylalkoxysilane of the formula G.l.p.c. analysis showed complete consumption of the CH3 disilane and the formation (20.5 and 19.7 area percent 1 respectively) of vinylalkoxysilanes of the formulae CH3C=CS1(OCH3)2 CH:

H CH3 CH C=( JSiOCHa EXAMPLE 4 i I H (CH3): To 21.0 grams (0.1 mol) of the dlsllane and CH CH3 1 a l cuaonsi-sitocum CH3 H CH3 3.2 grams (0.1 mol) of methanol was added at a rate of r EXAMPLE 7 10 ml./hour through a quartz tube heated to 400 C. When the materials indicated below were substituted for Simultaneously, 25 ml./hour of acetylene was introduced. the materials of Example 1, the following vinylalkoxy- G.l.p.c. analysis of the reaction admixture showed comsilanes were produced:

Disilane Alcohol Alkyne Vinylalkoxysilane CH3 (A) (CH O)2S]i-Si(OCH3)z Met-han0l Dimethylacetylene CH (F=(3Sii(OCH;) H

(([3Ha)2 (ll-Ha (B) n-C;H 0S1SiO C3H7-n CHQOHZCHZOH do CH C CSiOC PB-n (CH3): H (CH2):

102 1 o) n-cmmosFsuocmmTn n-cfirrmou @-c=o-@ @-o=os io C lin-n OH: H 102 and H CH

EXAMPLE 8 When the materials of Example 7 were substituted for the materials of Example 3, equivalent results were obtained.

That which is claimed is:

- 1. A method for preparing yinylalkoxysilanes comprising (A) contacting in a closed system (1) a disilane of the formula (RO) Sl si(oR H-n S-n in which R is an alkyl radical of from 1 to 6 carbon atoms inclusive,

R is selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms inclusive, and a phenyl radical,

n has a value of '1 to 2 inclusive, with (2) at least a stoichiometric amount of an alcohol of the formula ROH and an alkyne of the formula RCECR", in which R is as above defined,

R" is selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms inclusive, a phenyl radical, and a hydrogen atom,

(B) heating the above admixture to a temperature of at least about 175 C., and (C) thereafter recovering the vinylalkoxysilane. 2. The method as recited in claim 1 in which the disilane 1) is of the formula (3H3 (CHaO) 2SiS1i(O CH3)2 the alcohol (2) is methanol, and the alkyne (2) is dimethylacetylene.

3. The method as recited in claim 1 in which the disilane (1) is of the ofrmula (CHQM CHaOSiSiO CH3 the alcohol (2) is methanol, and the alkyne (2) is dimethylacetylene.

4. The method as recited in claim 1 in which the disilane (1) is of the formula (011m CHaOSiSIi(OCHa)z the alcohol (2) is methanol, and the alkyne (2) is dimethylacetylene.

in which R is an alkyl radical of from 1 to 6 carbon atoms inclusive,

R is selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms inclusive, and a phenyl radical,

n has a value of 1 to 2 inclusive, with (2) at least a stoichiometric amount of an alcohol of the formula ROH and an alkyne of the formula R"CECR", in which R is as above defined,

R" is selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms inclusive, a phenyl radical, and a hydrogen atom,

(B) heating the above admixture to a temperature of at least about 350 C., and (C) thereafter recovering the vinylalkoxysilane. 6. The method as recited in claim 5 in which the disilane of the formula CH3 (OH30)ZS i si(OCH3)2 the alcohol (2) is methanol, and the alkyne (2) is acetylene.

7. The method as recited in claim 5 in which the disilane is of the formula CHaO Si-SiO CH3 ((IJHQZ the alcohol (2) is methanol, and the alkyne (2) is acetylene.

8. The method as recited in claim 5 in which the disilane (1) is of the formula (CHa)2 CH3OSi-S|i(OCHa)2 the alcohol (2) is methanol, and the alkyne (2) is acetylene.

References Cited UNITED STATES PATENTS 2,881,197 4/1959 Kuriyagawa et al. 260448.8R 3,478,079 11/1969 Atwell 260-448.8R

TOBIAS E. LEVOW, Primary Examiner P. F. SHAVER, Assistant Examiner 

